The invention relates to a knife comprising a blade with a blade tang at one end, a handle and an insert, which can be assembled by joining the insert and the tang, and when assembled, the insert and the tang are fitted into a hole in the handle having a cross-section substantially equal to the cross-section of the insert portion to be fitted within the handle.
The manufacture of a knife usually comprises fitting of the blade tang into a hole in the centre of the handle and fastening of one end of the tang by riveting. This manufacturing method calls for a great number of manual operations. On the other hand, FI patent specification 87055 discloses a knife whose parts are assembled by gluing. Gluing has the major advantage of allowing automatised manufacture of the knife, which results in reduced production costs.
However, glued joints tend to dry, whereby the knife falls apart. Especially the operating conditions have a bearing on the durability of the glue; for instance, a number of glues have no cold resistance (at summer cottages, in boats, etc.). It may also be difficult to find a suitable glue when the different parts of the knife are made of different materials, for instance, the handle is made of wood, the blade of metal and the insert of plastic. Glue application also calls for complex machinery. On top of that, gluing frequently causes various gas and odour emissions to the working premises, such emissions being unpleasant in the working environment and perhaps even involving a health hazard.
Thus the object of the invention is to provide a knife that has a long and reliable service life under various circumstances and which is easy and rapid to manufacture without any risks for the working environment. These objects are achieved with the knife in accordance with the invention such as defined in the accompanying claims.
The invention thus relates to a knife comprising a blade with a blade tang at one end, a handle and an insert. The characterising feature of the knife in accordance with the invention is that at least part of the outer surface of the insert portion fitted within the handle is substantially a non-smooth surface. Said non-smooth surface is preferably a fluted surface.
Consequently, the assembly of the knife of the invention does not require any glue or rivets, the retention of the tang within the handle being ensured by means of the fluted insert surface. In this manner, the knife will have a service life of several years regardless of its operating conditions. The material creep will be so insignificant that it has no practical impact in this case.
In one embodiment of the invention, the walls in the grooves of said fluted surface are at a substantially different angle of inclination to the normal of the surface, and preferably the first groove wall adjacent to the blade is at a specific angle to the normal of the surface, and the second groove wall remote from the blade is substantially parallel with the normal of the surface. Such a groove design further enhances the retention of the tang within the handle.
In a further embodiment of the invention at least part of the insert portion fitted within the handle comprises a groove extending longitudinally through said insert. Preferably, the outer groove end viewed from the blade converges with the outer insert end viewed from the blade. By way of example, said groove length accounts for 30 to 100%, preferably 50 to 100%, most preferably for 80 to 100% of the length of the insert portion fitted within the handle.
In a preferred embodiment of the invention, an especially durable joint is provided when
the first inner wall of said groove comprises a projection,
the second inner wall of said groove is substantially plane, and
the blade tang comprises a notch having a shape substantially matching the projection of the first inner wall of the groove, so that said projection engages said notch with the insert and the blade tang assembled. Such a pair of projection-notch prevents any disengagement of the tang from the insert, for instance when the blade is being pulled at.
In a further embodiment of the invention at least the first portion of the surface of the insert portion fitted within the handle comprises two substantially parallel, substantially planar surfaces, and two mutually symmetric surfaces which are convex relative to the insert centre and connect said two surfaces. Then the first portion of the outer surface of the insert has a length that accounts for 30 to 100%, preferably 50 to 100%, most preferably 80 to 100% of the length of the insert portion fitted within the handle. In addition, said convex surfaces are preferably fluted and said preferably planar surfaces are preferably smooth.
The different parts of the knife of the invention can be manufactured of any material desired, such as for instance plastic, metal, wood, stone or a combination of at least two of these.
The insert of the knife of the invention may further be integrated with the ferrule member or not, or the insert may comprise a plurality of discrete parts.